Mine has an SP of 111 (Golden Chip). I can do -0.095 MAX. On mine 100% stable. But thats SERIOUSLY clock stretching. So reduced it to -0.085 if running just an Undervolt.
But with the heavy OC the best FULL STABLE UV I can do is -0.030 and With P-Cores Pushed to 6.0 and E- Cores pushed to 4.6 boost!? that much of an Undervolt is really good! Also never going over 84c with an OC!? Madness! With the OC+Undervolt it blows my buddy’s 13900ks away. He hates me. 
What? I’ve dual streamed with a ton of tabs open to 0 impact on my 7800X3D. Weird if it hurts your performance.
I’ve even played while rendering in the background, but that’s more demanding.
A lot of this depends on also what resolution you are streaming at wow will use up to 8 cores. Remember every little thing you using the background takes up resources so if you have a second monitor going with a bunch of things running on top of Gaming it’s going to hurt your gaming performance because you need roughly 8 cores for gaming.
So look at it this way it’s kind of like saying hey I have a 12-core CPU so 8 of my cores get dedicated to gaming and the stuff I’m running in the background causes absolutely zero hindrance to my gaming performance. How much it affects your performance depends on how much stuff you’re doing on your second monitor.
It’s obviously all comes down to use case. You are right though for the majority of the gamers an 8 core CPU is just fine and probably all they need
The main benefit to AMD is no tweaking. You literally turn on PBO2 and your done. My chip took hours of tweaking. Yet a 7800x3D would perform very close to the same as mine now out of the box.
That’s a very odd refresh rate.
While all I said above is true. What is also true and can not be denied is the fact that the X3D are an amazing Value.
Ill leave this here for anyone considering getting one
7600x vs 7950x3D (3D V-Cache) The difference is big. 7800x3D would be the same or slightly better. Keep in mind this is while using only a 6950xt and the GPU. This is at 4k too
Are you running software rendering for your streams or leveraging nvenc/your IGP?
Im not a streamer. I have friends in wow that are. I built most of their rigs. So was speaking from my experience with them and their rigs. 
When your LF III comes in reply saying if you had to reverse the brackets or not. Im highly curious
Looking at the board and cooler I have now, I don’t expect to need to, but I’ll keep you posted.
No issues at all with SSD heatsink clearance with the LFIII on the MSI X670E Tomahawk.
Love the specs. 
HATE THE PRICE. 
Easy. Go for LG C4 instead.
https://www.whathifi.com/reviews/lg-c4